Salt Questions · Science, chemistry & environment
What is the crystalline structure of sodium chloride?
Short answer
Sodium chloride forms a cubic crystal lattice, the “rock-salt” structure. Sodium and chloride ions alternate in all three directions, and each ion is surrounded by six of the opposite kind. Chemists describe it as two interlocking face-centred cubic lattices. That's why salt crystals grow and break as cubes.
The rock-salt lattice: each ion surrounded by six of the other
- Sodium ion, Na⁺ (smaller)
- Chloride ion, Cl⁻ (larger)
The rock-salt structure
- Each Na+ ion is surrounded by 6 Cl− ions, arranged at the corners of an octahedron, and vice versa.
- The repeating unit cell is a cube about 0.564 nanometres on each side, containing four sodium and four chloride ions.
- So many other compounds share it that the arrangement is named after salt.
Why it matters
The strong attraction between oppositely charged ions in every direction makes salt hard, brittle and high-melting (801 °C). It cleaves cleanly along flat planes, so crushed salt breaks into smaller cubes.
See it yourself
Look at table salt with a magnifying glass: most grains are tiny cubes. Flaky salts grow differently because they crystallise at the surface of the brine.
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Cite this page
For school projects and reports. Teachers often prefer the original sources too: see the list below.
The Salt Almanac. (2026, November 8). What is the crystalline structure of sodium chloride. https://saltalmanac.com/answers/what-is-the-crystalline-structure-of-sodium-chloride
“What is the crystalline structure of sodium chloride.” The Salt Almanac, 8 Nov. 2026, saltalmanac.com/answers/what-is-the-crystalline-structure-of-sodium-chloride. Accessed [today's date].
“What is the crystalline structure of sodium chloride.” The Salt Almanac. Last modified November 8, 2026. https://saltalmanac.com/answers/what-is-the-crystalline-structure-of-sodium-chloride.
Original sources
- Wikipedia. Sodium chloride. https://en.wikipedia.org/wiki/Sodium_chloride
- Wikipedia. Cubic crystal system. https://en.wikipedia.org/wiki/Cubic_crystal_system